The use of a prime-boost immunization schedule is well known. For example, children typically receive a variety of primary immunizations up to the age of 15 months (e.g. a DTPa vaccine) and then receive booster doses aged between 4-6 years and beyond (e.g. a Tdap vaccine). According to current schedules, though, the immune response elicited by a booster dose does not lead to rapid re-establishment of immunity (e.g. of protective antibody titers). Furthermore, the primary immunizations aim to provide immediate protection against diseases that affect the pediatric population, and the aim of a booster is to prolong this immediate protection.